for a STFT spectrum \(X\)  with bin indices \([0...n]\) . The result, which is linearly biased towards high frequencies, is then fed to a detection function that returns the predicted onset location. This detection function is based on both the high frequency energy flux between the two adjacent frames and the normalised high frequency content of the current frame. The implementation that this study follows is included in Aubio's AubioOnset [1]}. It has also been reported that the HFC method works especially well for vocal percussion [2]}.
